Ag 3 PO 4 -TiO 2 -graphene oxide ternary composite photocatalysts were fabricated by the photocatalytic reduction and ion exchange methods. The properties and photocatalytic activity of the composites were examined, and the photodegradation mechanism was investigated. More TiO 2 nanoparticles in the composites were found to improve light absorption, but caused a larger impedance and inferior charge transport. Excess TiO 2 nanoparticles distributed over the surfaces of Ag 3 PO 4 and graphene oxide decreased the specific surface area and thus lowered light absorbance. an appropriate TiO 2 content enhanced photocatalytic performance. When the molar ratio of Ag 3 PO 4 to TiO 2 was 0.6, the highest efficiency in photodegradation, hydrogen production (with a quantum efficiency of 8.1% and a hydrogen evolution rate of 218.7 µmole·g −1 ·h −1 ) and bacterial inactivation was achieved. Trapping experiments demonstrated that superoxide radicals and holes are the major active species involved in the photodegradation process.

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